The prior art includes mechanisms for actuating ground-implement brakes in various modes of operating conditions. For instance, where the implement is maneuvered over the ground by means of handlebars or hand grips, it is common to have a brake lever adjacent the hand grip for actuating the brake and thereby retard wheel rotation, as desired. However, in these instances, the prior art brakes are arranged so that the operator must continue to exert a hand-gripping pressure on the brake lever in order to actuate the brake. Accordingly, immediately upon releasing the brake lever, the brake itself is released by means of a spring force commonly applied to the brake and operative toward the released or non-braking position. That is, when the implement is unattended, it is free to roll or move over the ground because the brake is automatically released.
U.S. Pat. No. 4,558,558 shows one example of a prior art brake mechanism of the type mentioned above. In that arrangement, when the operator releases the brake lever, then the implement is free to roll or otherwise be maneuvered over the ground, and in the context of the present invention, that is undesirable. That is, the present invention provides for a parking brake lock which permits the operator to set the brake in a locked position and walk away from the implement which remains in the locked position and therefore cannot inadvertently roll over the ground.
U.S. Pat. No. 4,967,543 shows an arrangement of a control lever on the implement handlebar and wherein the lever can be set in multiple positions for the purpose of controlling the speed of the hydraulic motor driving the implement wheels. That is only a speed control lever arrangement, and it is not pertaining to a parking brake, even though the lever itself is mounted on the implement handlebar or adjacent the hand grip and can be maneuvered between different positions.
Beyond the aforementioned basic objective of this invention, the present invention also provides a parking brake lock which is operatively connected with the mechanism for placing the implement in a driving mode, such that the driving mode mechanism and the parking brake lock operate in unison, but with their respective and thus opposite effects of mobilizing the implement and securing the implement in an immobilized mode.
Still further, the present invention provides a parking brake lock which is combined with a wheel brake which can be set in various degrees of braking force operative on the wheels, and this permits the maneuverability of the implement by applying the wheel brake on one side of the implement, say the left side, and thereby have the implement move to the left side while the wheel on the right side is free to drive the implement in the left-turning direction.
Still further, the present invention provides a parking brake lock which is arranged for automatic compensation of wear of the various parts in the system, including the brake band and the like. Also, the arrangement is such that the system automatically accommodates the variability or interconnection of the various parts which comprise the system, such that the overall reach or length of the system from the actuating lever and down to the brake itself is automatically accommodated by virtue of this unique parking brake lock.
Still further, the parking brake lock of this invention provides for positioning the brake mechanism in an implement-running position as well as in the parking brake lock position, all incorporated into one lever. Still further, the one lever mentioned can be maneuvered either by the operator's thumb pressure adjacent the hand grip, or greater force and leverage can be applied to the lever by means of an additional lever arm incorporated in the lock member. In the ultimate, the single lock member provides for the function of locking the brake, and the function of holding the mechanism in a neutral position where there is no drive power applied to the wheels and there is no brake lock, and it provides for a third position where there is drive power to the wheels but again there is no brake lock. In the arrangement of these several positions, it is also a feature that if the brake lock is set in the lock position and the engine is running, if the lock is moved out of the lock position, inadvertently or intentionally, then the lock can normally go to a position which will still prevent the engine power from being transmitted to the driven wheels even though the system is in the non-parking brake mode. Further, the system is placed into the drive mode only by a specific maneuver of the parking brake lock, so that it cannot be acccidentally placed into the drive mode from the parking brake lock mode.
Other objects and advantages will become apparent upon reading the following description.